def is_prime(n): 
  if n <= 1: 
    return False 
  for i in range(2, int(n*0.5) + 1): 
    if n % i == 0: 
      return False 
  return True 
 
def find_closest_prime(n): 
  increment = 1 
  while True: 
    if is_prime(n + increment): 
      return n + increment 
    if is_prime(n - increment): 
      return n - increment 
    increment += 1 
 
words_to_digits = { 
  "zero": "0", "one": "1", "two": "2", "three": "3", "four": "4", 
  "five": "5", "six": "6", "seven": "7", "eight": "8", "nine": "9" 
} 
 
input_words = input().split() 
 
if len(input_words) != 3: 
  print("Wrong input") 
else: 
  try: 
    number_str = "".join([words_to_digits[word] for word in input_words]) 
    number = int(number_str) 
    print(find_closest_prime(number)) 
  except KeyError: 
    print("Wrong input")
